UPCAT General Science (Extended) — Atmosphere, Weather & ClimateCheat Sheet
One-page cheat sheet for UPCAT General Science (Extended) — Atmosphere, Weather & Climate. Every formula, definition, and key fact you need for this chapter, condensed to a single printable page. Designed for the final review session before the UPCAT 2026.
Exam context
On the UPCAT 2026, the General Science (Extended) subtest carries a "Extended coverage for UP Science programs" weight in University of the Philippines's pattern. Atmosphere, Weather & Climate lands at position 4th out of 6 in the standard review order. Target score is UPG ≤ 2.2 typical, and roughly 20 items come from General Science (Extended) on a typical UPCAT paper.
Atmosphere, Weather & Climate - Cheat sheet
Your last-minute revision companion for mastering atmospheric science concepts, weather patterns, and climate systems for the UPCAT exam.
Sections
Common Values
Value
78%
Symbol
N₂
Quantity
Nitrogen in atmosphere
Value
21%
Symbol
O₂
Quantity
Oxygen in atmosphere
Value
0-10 km
Symbol
h
Quantity
Troposphere height
Section Title
Atmospheric Composition & Structure
Important Facts
- Air pressure and temperature decrease with altitude in troposphere
- Ozone layer in stratosphere protects Earth from harmful UV rays
- Temperature increases in thermosphere due to solar radiation absorption
- Most satellites orbit in the thermosphere
- Aurora phenomena occur in thermosphere due to charged particles
Key Definitions
Term
Atmosphere
Example
The air we breathe in the troposphere
Definition
Layer of gases surrounding Earth: 78% nitrogen, 21% oxygen, 0.93% argon, 0.03% carbon dioxide
Term
Troposphere
Example
Contains 99% of water vapor and all clouds
Definition
Lowest atmospheric layer (0-10km) where weather occurs and we live
Term
Stratosphere
Example
Where commercial jets fly
Definition
Second layer (10-50km) containing ozone layer that absorbs UV radiation
Term
Mesosphere
Example
Temperature decreases with altitude
Definition
Third layer (50-85km) where meteors burn up
Term
Thermosphere
Example
Temperature rises sharply due to X-ray and UV absorption
Definition
Fourth layer (85-600km) where satellites orbit and auroras occur
Term
Exosphere
Example
Transition zone to outer space
Definition
Outermost layer where atmospheric particles escape to space
Term
Ionosphere
Example
Reflects radio waves for communication
Definition
Region in mesosphere and thermosphere where solar radiation ionizes atoms
Diagrams To Know
- Atmospheric layers diagram with altitude markers
- Temperature profile through atmospheric layers
Section Title
Weather Components
Important Facts
- Warm air rises creating low pressure systems (clouds and rain)
- Cold air sinks creating high pressure systems (clear skies)
- Wind flows from high pressure to low pressure areas
- Six main weather components: temperature, humidity, pressure, wind, precipitation, cloudiness
- Barometer measures atmospheric pressure
- Psychrometer measures humidity
Key Definitions
Term
Weather
Example
Today's temperature, humidity, and wind conditions
Definition
General atmospheric conditions at a specific time and place
Term
Climate
Example
Philippines has tropical maritime climate
Definition
Average weather conditions of a region over a long period (minimum 30 years)
Term
Temperature
Example
Measured with thermometer in Celsius or Fahrenheit
Definition
Measure of hotness or coldness of the atmosphere
Term
Atmospheric Pressure
Example
Decreases with altitude, measured with barometer
Definition
Pressure exerted by weight of air above, measured in millibars
Term
Humidity
Example
Measured with psychrometer
Definition
Amount of water vapor present in air, expressed as relative humidity percentage
Term
Precipitation
Example
Rain during monsoon season
Definition
Water vapor that cools below saturation point and falls as rain, snow, or hail
Diagrams To Know
- High and low pressure system diagrams
- Wind direction patterns
- Cloud formation process
Section Title
Wind Systems & Monsoons
Important Facts
- Wind flows from high pressure (cold) to low pressure (warm) areas
- Three major wind circulation cells: Hadley, Ferrel, and Polar
- Tropical easterlies flow in Hadley cell
- Prevailing westerlies flow in Ferrel cell
- Polar easterlies dominate Polar cell circulation
Key Definitions
Term
Wind
Example
Sea breeze from ocean to land during daytime
Definition
Movement of air caused by pressure and temperature differences between regions
Term
Coriolis Effect
Example
Hurricane rotation patterns
Definition
Deflection of moving objects due to Earth's rotation - right in Northern Hemisphere, left in Southern
Term
Hanging Amihan
Example
Cool, dry season in Philippines
Definition
Northeast Monsoon (Nov-Mar): cold, dry weather from Siberia
Term
Hanging Habagat
Example
Rainy season in western Philippines
Definition
Southwest Monsoon (Jun-Oct): hot, humid weather with heavy rainfall from Australia
Term
Trade Winds
Example
Transition period between monsoons
Definition
Mar-May winds from North Pacific Ocean bringing rain to eastern Philippines
Diagrams To Know
- Global wind circulation patterns
- Philippine monsoon wind directions
- Sea breeze and land breeze diagrams
Section Title
Clouds & Precipitation
Important Facts
- Cloud names combine altitude (cirro=high, alto=middle, low=no prefix) and type (cumulus=puffy, stratus=layer)
- Nimbo- or -nimbus means rain-bearing
- Cirrostratus creates halos around sun/moon - rain coming in 12-24 hours
- Cumulonimbus are most dangerous - produce severe weather
Key Definitions
Term
Clouds
Example
Formed when water vapor condenses as it cools
Definition
Masses of water droplets or ice crystals suspended in atmosphere
Term
Cirrus
Example
Scattered white streaks at high altitude
Definition
High, thin clouds like curls of hair - indicate fair weather
Term
Cumulus
Example
White, fluffy clouds on sunny days
Definition
Puffy, cotton-like clouds - fair weather clouds
Term
Stratus
Example
Overcast gray sky
Definition
Low, gray layer clouds - bring mist and drizzle
Term
Nimbostratus
Example
Continuous light to moderate rain
Definition
Thick, dark gray rain-bearing clouds
Term
Cumulonimbus
Example
Thunderstorms, lightning, tornadoes
Definition
Towering thunderhead clouds - bring severe weather
Diagrams To Know
- Cloud type identification chart
- Precipitation formation process
- Cloud altitude levels
Section Title
Weather Fronts
Important Facts
- Cold fronts move faster and bring more violent weather than warm fronts
- Stationary fronts can persist for days causing extended periods of rain
- Occluded fronts are complex systems with three air masses involved
Key Definitions
Term
Front
Example
Temperature and humidity change quickly
Definition
Boundary where two different air masses meet, causing abrupt weather changes
Term
Warm Front
Example
Gentle, steady rain followed by warming
Definition
Warm air mass replaces cold air - brings light rain then clearer weather
Term
Cold Front
Example
Sudden heavy rain, strong winds, temperature drop
Definition
Cold air mass replaces warm air - brings violent weather and thunderstorms
Term
Stationary Front
Example
Days of continuous drizzle
Definition
Air masses meet but don't move - prolonged rain and cloudy skies
Term
Occluded Front
Example
Complex weather system with multiple air masses
Definition
Cold front overtakes warm front - heavy rain and cooler weather
Diagrams To Know
- Cross-section diagrams of each front type
- Weather map symbols for fronts
- Air mass movement patterns
Common Values
Value
75%
Symbol
%
Quantity
Earth's surface covered by water
Value
97.2%
Symbol
%
Quantity
Saltwater percentage
Value
2.8%
Symbol
%
Quantity
Freshwater percentage
Section Title
Sea/Land Breezes & Hydrosphere
Important Facts
- Water has high heat capacity - warms and cools slowly
- Land has low heat capacity - warms and cools quickly
- This difference creates pressure differences and local wind patterns
- Ocean currents distribute heat around the globe
- Polar creep carries oxygen to deep ocean layers
Key Definitions
Term
Sea Breeze
Example
Cool ocean breeze during hot afternoons
Definition
Daytime wind from sea to land - land heats faster creating low pressure
Term
Land Breeze
Example
Wind blowing offshore at night
Definition
Nighttime wind from land to sea - land cools faster creating high pressure
Term
Hydrosphere
Example
Oceans, lakes, rivers, groundwater, ice, water vapor
Definition
All water on Earth - 75% of planet surface, 97.2% saltwater, 2.8% freshwater
Term
Surface Current
Example
Gulf Stream carrying warm water northward
Definition
Horizontal ocean water movement caused by wind force
Term
Deep Current
Example
Cold, dense water sinking at poles
Definition
Vertical ocean flow driven by temperature and salinity differences
Term
Upwelling
Example
Supports marine life by bringing nutrients up
Definition
Deep nutrient-rich water rising to surface
Diagrams To Know
- Sea breeze and land breeze formation
- Global ocean current patterns
- Upwelling process diagram
Must Remember
- Atmosphere composition: 78% N₂, 21% O₂, 0.93% Ar, 0.03% CO₂
- Troposphere (0-10km) is where we live and weather occurs
- Ozone layer in stratosphere protects from UV radiation
- Philippine monsoons: Amihan (NE, Nov-Mar, dry), Habagat (SW, Jun-Oct, wet)
- Wind flows from high pressure (cold) to low pressure (warm)
- Coriolis effect: deflects moving objects right in Northern Hemisphere
- Sea breeze: day wind from sea to land; Land breeze: night wind from land to sea
- Cumulonimbus clouds bring severe weather including thunderstorms
- Cold fronts bring violent weather; warm fronts bring gentle rain
- Earth is 75% water: 97.2% saltwater, 2.8% freshwater
Last Minute Tips
- Remember cloud prefixes: cirro=high, alto=middle, no prefix=low; nimbo=rain
- For Philippine weather: Amihan is cool NE wind (winter), Habagat is warm SW wind (summer rain)
- Atmospheric layers in order: Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere
- Weather vs Climate: Weather is now, Climate is average over 30+ years
- Pressure systems: Low pressure = rising air = clouds/rain; High pressure = sinking air = clear skies
Comparison Tables
Rows
Values
- November-March
- June-October
- March-May
Property
Season
Values
- Northeast
- Southwest
- East
Property
Direction
Values
- Siberia
- Australia
- North Pacific Ocean
Property
Origin
Values
- Cold, dry, little rain
- Hot, humid, heavy rain
- Rain on eastern coast only
Property
Weather
Values
- Entire Philippines
- Western Philippines
- Eastern Philippines
Property
Affected Areas
Columns
- Characteristic
- Hanging Amihan
- Hanging Habagat
- Trade Winds
Table Title
Philippine Monsoons Comparison
Rows
Values
- Thin, wispy, curl of hair
- High
- Fair weather
Property
Cirrus
Values
- Puffy, cotton-like
- Low-Medium
- Fair weather
Property
Cumulus
Values
- Gray, layered
- Low
- Drizzle, mist
Property
Stratus
Values
- Thick, dark gray
- Low-Medium
- Steady rain
Property
Nimbostratus
Values
- Towering, anvil-shaped
- All levels
- Severe weather, storms
Property
Cumulonimbus
Columns
- Cloud Type
- Appearance
- Altitude
- Weather Indication
Table Title
Cloud Types and Weather Prediction
Rows
Values
- Warm air replaces cold
- Light rain, then clear
- Gradual change
Property
Warm Front
Values
- Cold air replaces warm
- Heavy rain, thunderstorms
- Quick, violent
Property
Cold Front
Values
- No movement
- Prolonged rain, clouds
- Extended period
Property
Stationary Front
Values
- Cold overtakes warm
- Heavy rain, cooling
- Complex system
Property
Occluded Front
Columns
- Front Type
- Movement
- Weather Brought
- Duration
Table Title
Weather Fronts Comparison
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